Weft thread-cutting mechanism for shuttleless looms



0a. 17, 1967 N. Komms 3,347,282

WEFT THREAD-CUTTING MECHANISM FOR SHUTTLELESS LOOMS Filed Dec. 15, 1965 2 Sheets-Sheet 1 FIG. .2

FIG. I

INVENTOR NIKOLAUS KOKKINIS BY ow ATTORNEY Oct. 17, 1967 N. KOKKINIS 3,347,232

WEFT THREAD-CUTTING MECHANISM FOR SHUTTLELESS LOOMS Filed. Dec. 15, 1965 2 Sheets-Sheet 2 FIG. 7 13%;

INVENTOR NIKOLAUS KOKKINIS BY M a ATTORNEY United States Patent L 4 Claims. (Cl. 139-116) ABSTRACT OF THE DISCLOSURE This invention relates to a weft thread cutting mechanism for use in shuttleless looms which eliminates the disadvantages and drawbacks of known arrangements of cutting off or severing weft threads in a fabric in a simple manner so that in shuttleless looms in which weft threads are inserted by means of gripper systems, the threads may be inserted individually and no complicated embedding apparatus is required to form an edge. The mechanism of the present invention includes an arm which is pivotally mounted On an axle or shaft, the movement of the arm being coupled with the weft thread-inserting device. The arm carries, at the end thereof, a fixed and a movable jaw, the tips of which jaws extend through the warp threads of the shed in one of the end positions of an oscillating movement of the arm and, in such position, sever the weft thread between the jaws. The movable jaw is closed on the fixed jaw so that no gap exists between them and the action of the jaws is coordinated with the weft thread-inserting device.

In shuttleless looms, the weft thread is drawn off from large supply spools and inserted either in the form of individual threads or as U-shaped loops. When operating in this manner, the required length of the weft thread must be measured and cut off each time. In looms which insert the weft thread in a U-shaped loop, for example by means of gripper systems, special clamping and cutting means generally must be provided between the supply spool and the selvage for this purpose. The thread is cut off in such a manner that the free end thereof can be drawn through the shed and extends just across the weaving width. Under certain circumstances, the thread even extends slightly over at the other side. The end of the thread which is still connected to the supply spool is held in position and placed in readiness for the next weft insertion. Known cutting means are, for example, scissors which are mounted close to the edge of the fabric, these scissors being stationary and comprising only movable blades.

Due to the U-shape of the weft threads, a natural selvage is formed. If the weft thread is inserted alternately from both sides, a selvage is obtained on both sides and short free thread ends being positioned between the U- sh-aped loops possibly may still extend out over the selvage. An edge is maintained, however, at both sides. Different conditions prevail if the Weft threads are inserted individually, for example by means of gripper shuttles. In this case, the weft thread ends will extend out and over somewhat on both sides of the fabric and are cut off outside of the latter. A known arrangement uses a rotary knife to cut the weft thread between the fabric and the clamping jaw. Other known arrangements employ scissors which are collectively advanced and then closed in the advanced position. After the cutting operation, the scissors are withdrawn. In the course of this weaving method, a natural selvage is not produced and special means must be provided for embedding the weft thread ends; the known embedded or turned edges are thus formed. In one known arrangement, the weft threads on the finished fabric are subsequently cut off, by means of scissors, between the fabric proper and the turned threads.

The problems are similar when inserting the weft thread by means of gripper systems where the grippers are mounted on bands, rods and the like, which are adapted to be advanced and retracted. If it is intended to insert a single weft thread, the free weft thread end is conventionally drawn through the shed so that it terminates on the opposite side. During the second Weft operation, a U-shaped loop is customarily formed. In a known arrangement the gripper point or tip which has the function of grasping and inserting the weft thread is so designed that the weft thread breaks or is torn off at the gripper point or tip. The torn-off end of the first weft operation is placed between the first warp threads in a U-shaped or hookshaped manner. The other weft thread end, which is still connected with the supply spool, is completely carried through the shed by the gripper system. In this manner, an edge will be automatically formed without requiring the aforementioned special means. This arrangement has the significant disadvantage, however, that the gripper point or tip must be designed even more intricately and, further, in the process of breaking or tearing-off not only the weft threads themselves but the entire fabric positioned in proximity to the edge will be excessively stressed. The concept of causing the weft thread not to be torn-off by the gripper point or tip butto cut it off instead with a knife or scissors involves difficulties since, in any event, the knife or scissors must pass be tween the warp threads.

Also known in the art is an arrangement wherein a knife is periodically advanced into the shed between and through the warp threads from below. The cutting of the weft thread however does not always proceed in a perfect manner because the weft thread tends to slip away and often is either not cut off accurately or is not cut off at all. Also, the use of scissors passing between the warp threads entails difficulties. The scissor members must have a certain amount of strength for reasons of rigidity. In view of the fact that the scissor members pass through side-byside, double the width of the individual scissor blades is required. Such width between the warp threads is, however, not desirable. Furthermore when using scissors, the weft thread tends to slip away from between the two blades so that, in this case also, specific means must be additionally provided in order to properly grip and cut off the weft thread.

The invention will be further illustrated by reference ,to the accompanying drawings in which:

FIGURE 1 is a view in elevation of one embodiment of the weft thread-cutting mechanism of the present invention,

FIGURE 2 is a view of the mechanism of FIGURE 1 looking in the direction of arrow A in FIGURE 1,

FIGURE 3 is a sectional view, in an enlarged scale, through the fixed and movable jaws of the weft threadcutting mechanism taken on line B-B of FIGURE 1,

FIGURES 4, 5, and 6 illustrate the fixed and movable jaws of the weft thread-cutting mechanism with a pressing finger additionally mounted on the movable jaw, and

FIGURE 7 is a sectional view of a fabric showing the combined action of the aforementioned elements.

The weft thread inserting device includes an arm 1 which has a curved shape, in the embodiment shown in FIGURE 1, and is rotatably mounted on the shaft 2. Opposite to the arm 1 is the extension 11 which has a cam follower roller 12 thereon, which latter engages with the r 3 cam surface of a cam plate 20. The cam plate 20 is driven by the shaft 21, which latter is coupled with the loom drive and also with the weft thread-inserting device, in a manner not shown, so that the arm 1 has a swing ing movement toward the shed imparted thereto after each weft thread insertion. A spring 15 secured at 16 to the arm 1 serves to return the arm to its original position. The lateral coordination of the swinging movement of the arm with the movements of the weft thread-inserting device and the weaving batten or sley 19, shown in phantom in FIGURE 1, is thus assured.

The arm has, at the end thereof, two jaws 3 and 4. In the embodiment shown in FIGURE 1, the lower jaw 3 is fixed and is rigidly mounted on the arm 1. The upper jaw 4, on the other hand, is movable and rotatable about the axle or pin 5. This movable jaw 4, together with the arm 6, constitutes a toggle or angle lever, the lever arm 6 being constructed as a laminated spring and carrying a cam follower roller 7 which engages a cam surface on the cam plate 8. The profile of cam 8, through roller 7 and arm 6 causes jaw 4 to move to the closed or cutting position and also allows the jaw to return to the open position. The return of the movable jaw 4 is effected by means of the return spring 9. The cam plate 8 is rigidly connected with a disc or plate 10, for example by means of the bolts 23 or other similar elements, and the disc or plate 10, in turn, is rigidly mounted on the shaft 2 by means of a screw 22 or other equivalent means. The shaft 2 also is coupled with the loom drive so that the cam plate 8, being driven by the shaft 2, will continuously rotate. The cam plate is mounted coaxially with respect to the axis of oscillation of the arm 1. The movements of the movable jaw 4, which are controlled by the cam plate 8, are so coordinated to the swinging movement of the arm 1 that the latter will pass into the shed between the warp threads 17 and 18, in one of the end positions of the oscillating movement, as has been shown in phantom dashed-dotted lines in FIGURE 1.

As a result of the position of the cam plate 8, the tips of the fixed and movable jaws are opened and will assume the position shown at 3' and 4 in FIGURE 1. When the cam plate 8 is further rotated, the movable jaw will be again closed on the fixed jaw, at which time the movable jaw will be positioned flush and without any gaps on the stationary jaw 3, with the result that the weft thread therebetween is severed. The force required for severing the weft thread is obtained by means of an adjustable excess stroke of the cam plate 8 in cooperation with the spring or elastic property of the lever arm 6. After severing the weft thread, the entire arm 1 with the fixed and movable jaws 3 and 4 thereof, swings back once more into the position of rest which is shown in solid lines in FIGURE 1.

FIGURE 3 illustrates, at a and b, in cross-section, two different configurations of the tips of the jaws 3 and 4, in an enlarged scale. The stationary jaw 3 has a fiat upper surface 13. The oppositely-positioned movable jaw 4 has a wedge shape and, for example, the faces 14 may provide a wedge-like configuration having an angle of 90 between them. The apex of the wedge is not constituted as a cutting edge but, instead, is rounded off. As a result, the weft thread is not cut off as with scissors but is clamped in and thereby severed. The jaws also may have other configurations and it is essential only that the flat portion and the wedge shaped portion are pressed upon one another in a manner such that no gaps exist between them. The two jaws 3 and 4 are, in each case, no wider than one scissor element would need be but, since they are not positioned side-by-side but rather superimposed flush with respect to each other, a con siderable reduction in width is achieved. They satisfy all requirements with regard to the strength thereof. Due to the fact that the two jaws 3 and 4 are superimposed in a manner so that there are no gaps, the weft thread can not slip away, and, accordingly, a faultless severing of.

the weft thread is effected at all times.

The separation of the weft threads is always perfectly effected at the predetermined place so that a neat, clean edge is formed. Certain difficulties, however, can arise on occasion, i.e., in weft threads made from a stiff material there exists the tendency that the severed short ends, after being separated, do not remain bent around within the shed but tend to skip or slip out of the shed. This produces an uneven and faulty edge. In order to prevent this, an additional pressing finger in the form of a small plate or the like is provided on the movable jaw in accordance with a further feature of the present invention.

In FIGURES 4 to 7, the pressing finger and the operation thereof are schematically illustrated. The pressing finger 24 is secured to the side of the movable jaw 4, for example by means of a machine screw 25. The finger preferably is provided as a small flat plate and is so mounted that it is adapted to be inserted into the shed and, with the edge thereof, press the cutoff end of the weft thread into the corner geing formed by the upper and lower shed. The distance between the movable jaw 4 and the pressing finger 24 may be adjusted, for example by the use of spacer members 28 of varying length. In the open condition of the jaws 3 and 4, as illustrated in FIGURE 5, the movable jaw 4, as well as the pressing finger 24, remain either completely or at least substantially outside of the shed. The weft thread 27 proceeds in its course in the shed, formed 'by the warp threads 17 and 18, respectively, without encountering any obstacles. In order to sever the weft thread, the jaws 3 and 4 are closed as shown in FIGURE 6. The point or tip of the pressing finger 24 will then laterally project beyond the tip of the stationary jaw 3. The weft thread is severed, in the manner described above, by the jaws 3 and 4 and the short bent-over end 27 of the weft thread is thereby pressed, by the pressing finger 24, against the preceding weft threads, The correlation between the various elements is illustrated in FIGURE 7. It is apparent from FIGURE 7 how the jaws 3 and 4 are inserted between the warp threads 17 and there sever the weft thread. The severed and short bentover end 27 of the weft thread is pressed, by the pressing finger 24, against the preceding weft threads 26. At this time, the friction of the weft thread end 27 at the warp threads is so great that the short bent-over end 27 of the Weft thread will no longer skip out until the shed is changed, even when the jaws 3 and 4 and the pressing finger 24, respectively, are once again retracted. As is further apparent from FIGURE 7, a clean edge having the width K is produced. As further described below, the width of the edge may be regulated by a lateral displacement of the cutting mechanism and, respectively, the jaws 3 and 4 thereof. The proportions have been illustrated in a slightly exaggerated manner; in actuality, the gap which is produced in the warp threads 17 by the jaws 3 and 4 is only approximately from 1 to 1.5 mm. wide, i.e., it is narrower than could be the case when using scissors.

A weft thread-cutting device of the type described herein may, of course, be mounted on both edges of the fabric and may be axially displaceable, if desired in conjunction with other structural elements of the loom, for example with the temple, in a manner such that a coordination and adaptation to different widths of fabric is made possible thereby. The width of the desired weaving border may be adjusted, in the same manner, by a lateral displacement of the weft thread-cutting mechanism as required in a particular case. The cut-off and bent-over weft thread ends are equally long at all times and are neatly and evenly embedded between the warp threads so that a flawless selvage is formed.

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is:

1. A weft thread-cutting mechanism for a shuttleless loom which comprises an arm pivotally mounted on a supporting shaft and having a fixed and a movable jaw at one end thereof, means for oscillating the arm so that the jaws are inserted between and retracted from between warp threads of a shed, and means for closing the movable jaw on the fixed jaw while the latter are between warp threads, whereby a weft thread between the jaws is severed.

2. A weft thread-cutting mechanism according to claim 1 in which the movable jaw is a part of an angle lever which is rotatably mounted on the arm, and including cam means for actuating the movable jaw.

3. A weft thread-cutting mechanism according to claim 2 in which one part of the angle lever has a cam follower at the end thereof, said latter part of the lever being a laminated spring.

4. A weft thread-cutting mechanism according to claim 2 in which the cam means for actuating the movable jaw rotates coaxially with the axis of oscillation of the arm.

5. A weft thread-cutting mechanism according to claim 1 in which the fixed jaw has a fiat weft thread-engaging surface and the movable jaw has a Weft thread-engaging surface in the shape of a rounded off wedge.

6. A weft thread-cutting mechanism according to claim 1 in which the means for oscillating the arm includes cam means.

7. A weft thread-cutting mechanism according to claim 1 in which the arm is mounted on the supporting shaft in an axially displaceable manner.

8. A weft thread-cutting mechanism according to claim 1 in which the movable jaw has means mounted thereon for pressing a severed weft thread end against finished fabric.

9. A weft thread-cutting mechanism according to claim 8 in which the means mounted on the movable jaw for pressing a severed weft thread end against finished fabric is a substantially flat depending plate.

10. A weft thread-cutting mechanism according to claim 9 including means for adjustably mounting the plate on the movable jaw, whereby the distance between them can be varied.

References Cited UNITED STATES PATENTS 5/1963 Dewas 139122 8/1965 Ancet et al. 139-122 FOREIGN PATENTS 808,75 5 11/1936 France.

MERVIN STEIN, Primary Examiner.

HENRY S. IAUDON, Examiner. 

1. A WEFT THREAD-CUTTING MECHANISM FOR A SHUTTLESS LOOM WHICH COMPRISES AN ARM PIVOTALLY MOUNTED ON A SUPPORTING SHAFT AND HAVING A FIXED AND A MOVABLE JAW AT ONE END THEREOF, MEANS FOR OSCILLATING THE ARM SO THAT THE JAWS ARE INSERTED BETWEEN AND RETRACTED FROM BETWEEN WARP THREADS OF A SHED, AND MEANS FOR CLOSING THE MOVABLE JAW ON THE FIXED JAW WHILE THE LATTER ARE BETWEEN WARP THREADS, WHEREBY A WEFT THREAD BETWEEN THE JAWS IS SEVERED. 